In rare cases, if Rh disease is not treated, the baby may die.Īn Rh test is done in early pregnancy to check a woman's blood type. After sensitization has occurred, the baby can develop mild to severe problems (called Rh disease or erythroblastosis fetalis). But the health of a baby with Rh-positive blood during a future pregnancy is more likely to be affected. Rh sensitization does not generally affect the health of the baby during the pregnancy in which the sensitization occurs. This antibody response is called Rh sensitization and, depending on when it occurs, can destroy the baby's red blood cells. If the blood of an Rh-positive baby mixes with the blood of an Rh-negative mother during pregnancy or delivery, the mother's immune system makes antibodies. A problem can occur when a woman who has Rh-negative blood becomes pregnant with a baby (fetus) that has Rh-positive blood. Rh blood type is even more important for pregnant women. If your blood has the B antigen but not the Rh antigen, your blood type is B-negative (B–). Do not have the Rh antigen, your blood is Rh-negative.įor example, if you have the A and Rh antigens, your blood type is A-positive (A+).Have the Rh antigen, your blood is Rh-positive.Rh blood type checks for the Rh antigen (also called the Rh factor) on red blood cells. Serious transfusion reactions are rare today because of blood type tests. So they are also checked for a match before giving a blood transfusion. Minor antigens (other than A, B, and Rh) that occur on red blood cells can sometimes also cause problems. Although 'universal donor' and 'universal recipient' types may be used to classify blood in an emergency, blood type tests are always done to prevent transfusion reactions. Type AB-positive blood is called the 'universal recipient' type because a person who has it can receive blood of any type. It is called the 'universal donor' type because it is compatible with any blood type. Type O-negative blood does not have any antigens. A transfusion reaction can be mild or cause a serious illness and even death. This is called a transfusion reaction, and it occurs immediately when incompatible blood is transfused.

If you get a transfusion that has different antigens (incompatible blood), the antibodies in your plasma will destroy the donor blood cells. have type AB blood, with 1% having AB-negative (AB-) blood and 4% having AB-positive (AB+) blood.īlood received in a transfusion must have the same antigens as yours (compatible blood). About 5% of people (5 in 100) in the U.S. Your plasma does not have antibodies against type A or type B blood. have type O blood, with 9% having O-negative (O-) blood and 39% having O-positive (O+) blood. About 48% of people (48 in 100) in the U.S. Your plasma has antibodies that attack both type A and type B blood. have type B blood, with 2% having B-negative (B-) blood and 9% having B-positive (B+) blood. About 11% of people (11 in 100) in the U.S. Your plasma has antibodies that attack type A blood. About 36% of people (36 in 100) in the United States have type A blood, with 6% having A-negative (A-) blood and 30% having A-positive (A+) blood. The liquid portion of your blood (plasma) has antibodies that attack type B blood. If your red blood cells have: The A antigen. The ABO test shows that people have one of four blood types: A, B, AB, or O. So the two most common blood type tests are the ABO and Rh tests.

The most important antigens are blood group antigens (ABO) and the Rh antigen, which is either present (positive, +) or absent (negative, -). Blood type tests may also be done to see if two people are likely to be blood relatives. Human blood is typed by certain markers (called antigens) on the surface of red blood cells. Blood type tests are done before a person gets a blood transfusion and to check a pregnant woman's blood type.

Universal blood typ